Significant efforts are currently invested in application integration to enable the interaction and composition of business processes of different companies, yielding complex; multi-party processes. Web service standards, based on WSDL, have been adopted as a process-to-process communication paradigm. This paper presents an industrial experience in integrating data-intensive and process-intensive Web applications through Web services. Design of sites and of Web services interaction exploits modern Web engineering methods, including conceptual modeling, model verification, visual data marshalling and automatic code generation. In particular, the applied method is based on a declarative model for specifying data-intensive Web applications that enact complex interactions, driven by the user, with remote processes implemented as services. We describe the internal architecture of the CASE tool that has been used, and give an overview of three industrial applications developed with the described approach.